Legacy Storage vs. Software Defined Storage at IBM Edge2015

At Edge2015 software defined storage (SDS) primarily meant IBM Spectrum Storage, the new storage software portfolio designed to address data storage inefficiencies by separating storage functionality from the underlying hardware through an intelligent software layer. To see what DancingDinosaur posted on Spectrum Storage in February when it was unveiled click here. Spectrum became the subject of dozens of sessions at the conference. Check out a general sampling of Edge2015 sessions here.

Jon Toigo, a respected storage consultant and infuriating iconoclast to some, jumped into the discussion of legacy storage vs. SDS at a session provocatively titled 50 Shades of Grey. He started by declaring “true SANs never reached the market.” On the other hand, SDS promises the world—storage flexibility, efficiency, avoidance of vendor lock-in, and on and on.

Courtesy Jon Toigo (click to enlarge)

What the industry actually did as far as storage sharing, Toigo explained, was provide serial SCSI over a physical layer fabric and the use of a physical layer switch to make and break server-storage connections at high speed. Although network-like there was no management layer (which should be part of any true network model, he believes). Furthermore, the result was limited by the Fibre Channel Protocol and standards designed so that “two vendors could implement switch products that conformed to the letter of the standard…with absolute certainty that they would NOT work together,” said Toigo. iSCSI later enabled storage fabrics using TCP/IP, which made it easier to deploy the fabric since organizations already were deploying TCP/IP networks for other purposes.

Toigo’s key requirement: unified storage management, which means managing the diversity and heterogeneity of the arrays comprising the SAN. The culprit preventing this, as he sees it, are so call value-add services on array controllers that create islands of storage. You know these services: thin provisioning, on-array tiering, mirroring, replication, dedupe, and more. The same value-add services are the culprits driving the high cost of storage. “Storage hardware components are commoditized, but value-add software sustains pricing.”

With Spectrum Storage IBM incorporates more than 700 patents and is designed to help organizations transform to a hybrid cloud business model by managing massive amounts of data where they want it, how they want it, in a fast and easy manner from a single dashboard. The software helps clients move data to the right location, at the right time to flash storage for fast access or to tape and cloud for the lowest cost.

This apparently works for Toigo, with only a few quibbles: vendors make money by adding more software, and inefficiency is added when they implement non-standard commands. IBM, however, is mostly in agreement with Toigo. According to IBM, a new approach is needed to help organizations address [storage] cost and complexity driven by tremendous data growth. Traditional storage is inefficient in today’s world. However, Spectrum Storage software, IBM continued, helps organizations to more efficiently leverage their hardware investments to extract the full business value of data. Listen closely and you might even hear Toigo mutter Amen.

SDS may or may not be the solution. Toigo titled this session fifty shades of grey because the vendors can’t even agree on a definition for what constitutes SDS. Yet, it is being presented as a panacea for everything that is wrong with legacy storage.

The key differentiator for Toigo is where a vendor’s storage intelligence resides; on the array controller, in the server hypervisor, or part of the software stack. As it turns out, some solutions are hypervisor dedicated or hypervisor dependent. VMware’s Virtual SAN, for instance, only works with its hypervisor. Microsoft’s Clustered Storage Spaces is proprietary to Microsoft, though it promises to share its storage with VMware – simple as pie, just convert your VMware workload into Microsoft VHD format and import it into Hyper-V so you can share the Microsoft SDS infrastructure.

IBM Spectrum passes Toigo’s 50 Shades test. It promises simple, efficient storage without the cost or complexity of dedicated hardware. IBM managers at Edge2015 confirmed Spectrum could run on generic servers and with generic disk arrays. With SDS you want everything agnostic for maximum flexibility.

Toigo’s preferred approach: virtualized SDS with virtual storage pools and centralized select value-add services that can be readily allocated to any workload regardless of the hypervisor. DancingDinosaur will drill down into other interesting Edge2015 sessions in subsequent posts.

DancingDinosaur is Alan Radding, a veteran IT analyst and writer. Please follow DancingDinosaur on Twitter, @mainframeblog. See more of his IT writing on Technologywriter.com and here.